Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and the like. Wireless communication networks that include a number of base stations to provide coverage over a wide geographic area may be called cellular networks. These cellular networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources.
Cellular networks have employed the use of various cell types, such as macrocells, microcells, picocells, and femtocells, to provide desired bandwidth, capacity, and wireless communication coverage within service areas. Some of the various types of cells may be used to provide wireless communication in areas of poor network coverage (e.g., inside of buildings), to provide increased network capacity, and to utilize broadband network capacity for backhaul. It may be desirable to distribute cells in areas where a direct network connection for providing backhaul is not available. Providing wireless backhaul to these cells provides challenges because of the high quality of service (QoS) requirements and limited backhaul spectrum availability.
Spectrum bands that permit unlicensed use have great potential for wireless backhaul. In the United States for example, unlicensed spectrum bands include spectrum around 915 MHz, 2.4 GHz, 3.4-3.8 GHz, 5 GHz, and 5.8 GHz in some areas. However, use of unlicensed spectrum bands presents challenges with regard to preserving channel reliability for carrier-grade deployments in the presence of licensed users and/or other wireless devices such as wireless local area network (WLAN) devices sharing the spectrum. For example, some bands may have primary users that have priority for use of channels within the band. Some bands may require unlicensed devices to detect the presence of licensed users and vacate the channel if the licensed users are detected. For example, Dynamic Frequency Selection (DFS) is a mechanism that allows unlicensed devices to use some bands already allocated to other uses without causing interference to the primary users. In addition, neighboring devices sharing the unlicensed band may generate bursty interference which may result in poor channel reliability. These and other issues may prevent effective deployment of carrier-grade wireless backhaul using unlicensed spectrum bands.